Pressurized lubricating system for a reciprocating compressor drive

ABSTRACT

A reciprocating compressor drive for driving a pair of opposed horizontally arranged compressor pistons. The pistons are carried by a pair of coaxial horizontal piston rods which are fixed to a crosshead situated between the piston rods and formed with a vertical slot receiving a slide block connected to a crank pin which is driven by a rotary crank drive. A pair of guide bars, which are parallel to the piston rods, extend through upper and lower bores of the crosshead, these bores carrying suitable bearings which slide along the guide bars. A pressurized lubricating system is provided for lubricating components such as the bearings which slide on the guide bars and the crank pin which is received in the slide block, the crosshead preferably being made of a light-weight material such as a plastic and carrying steel guide strips which slidably engage the slide block, the latter as well as the bearings which engage the guide bars preferably being made of bronze while the guide strips which engage the slide block and the guide bars which engage the bearings are preferably made of steel.

United States Patent Schroeder 22 Filed:

[4 1 Nov. 18, 1975 PRESSURIZED LUBRICATING SYSTEM FOR A RECIPROCATINGCOMPRESSOR DRIVE Nov. 26, 197 3 21 Appl. No.:419,148

Related US. Application Data [63] Continuation-in-part of Ser. No.119,478, March 1,

1971, Pat. NO. 3,779,672.

[30] Foreign Application Priority Data 308/238, DIG. 9, 493; 417/534,535, 536; 74/44, 49, 50; 184/5, 100, 6

Primary E.\'aminer-Richard C. Pinkham Assistant ExaminerMarvin SiskindAttorney, Agent, or Firm-Steinberg & Blake [57] ABSTRACT A reciprocatingcompressor drive for driving a pair of opposed horizontally arrangedcompressor pistons. The pistons are carried by a pair of coaxialhorizontal piston rods which are fixed to a crosshead situated betweenthe piston rods and formed with a'vertical slot receiving a slide blockconnected to a crank pin which is driven by a rotary crank drive. A pairof guide bars, which are parallel to the piston rods, extend throughupper and lower bores of the crosshead, these bores carrying suitablebearings which slide along the guide bars. A pressurized lubricatingsystem is provided for lubricating components such as the bearings whichslide on the guide bars and the crank pin which is received in the slideblock, the crosshead preferably being made of a light-weight materialsuch as a plastic R f C d and carrying steel guide strips which slidablyengage 1 UNITE]; gszr fg LZ the slide block, the latter as well as thebearings which engage the guide bars preferably being made of 2,183,87812/1939 Young 184/5 bronze while the guide Strips Which engage the Slide3 block and the guide bars which engage the bearings 3:033:312 5/1962Enders .1: 1:: 74/50 are preferably made of Steel 3,162,268 12/1964Short 184/5 9 Claims, 4 Drawing Figures 3,779,672 12/1973 Schroeder417/493 11 I 1 1 m111ll 30 flIIl/l 1 1 1 '11 1 1? end 1 i 2;

\1: 1111 $1 8 42 a4 44 v 28 H v I Ill-III" a EEITTITTAEVAR 7 luv lg WA,2. 1. I "f 7 v r I "I I I" "QYA J 'lilllll,lllzl'l 36 l {4 6 V E J 4Iili'AV/l US. Patent Nov. 18, 1975 Sheet 1 of3 3,920,098

US. Patent Nov. 18, 1975 FIG. 3

U.S. Patent Nov. 18, 1975 Sheet 3 of3 3,920,098

lllu PRESSURIZED LUBRICATING SYSTEM FOR A RECIPROCATING COMPRESSOR DRIVECROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of application Ser. No. 119,478, filed Mar. 1,1.971, and entitled AIR COMPRESSOR, now U.S. Pat. No. 3,779,672.

BACKGROUND OF THE INVENTION The present invention relates toreciprocating drives, and in particular to reciprocating drives forcompressors having horizontally arranged opposed pistons.

For certain purposes it is desired to arrange compresduly stressed. Alsoit is essential to provide parts which will not rapidly wear, so that along operating life can be assured for drives of this type.

SUMMARY OF THE INVENTION It is accordingly a primary object of thepresent invention to provide a drive of the above type which will solvethe above problems.

In particular, it is an object of the invention to provide areciprocating drive, particularly adapted for opposed compressorpistons, capable of operating extremely high speeds without subjectingthe components to excessive stresses or wear so that a long operatinglife is assured.

Furthermore it is an object of the present invention to provide for adrive of the above type alubricating system which will assure a longoperating life.

Also it is an object of the present invention to provide for areciprocating drive of the above type components made of materials whichwill contribute to a highly effective operation with minimummaintenance.

According to the invention the opposed compressor pistons are carried bya pair of horizontal coaxial piston rods fixed to a crosshead meanswhich is situated between the piston rods and which is formed with averti- 'cal slot. A slide block is received in this vertical slot and isoperatively connected with a crank pin which in turn is connected to arotary crank drive. The crosshead means is formed with upper and lowerbores which are parallel to the common axis of the piston rods and whichcarry in their interiors bearings which surround and are slidable alonga pair of guide bars carried by a housing means in which the guide barsas well as the crosshead means and the rotary crank drive are situated.A pressurized lubricating system is also carried by the housing meansfor lubricating such components as the crank pin and the bearings whichslide along the guide bars.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way ofexample in the accompanyingdrawings which form part of this applicationand in which: I

FIG. 1 is a simplified schematic front elevation of a compressorprovided with the reciprocating drive of the invention;

FIG. 2 is a fragmentary sectional plan view taken along line 2-2 of FIG.1 in the direction of the arrows and showing components of the inventionat a scale which is considerably enlarged compared to FIG. 1;

FIG. 3 is a fragmentary sectional elevation taken along line 3-3of FIG.2 in the direction of the arrows and showing further details of thedrive of the invention; and

FIG. 4 is a sectional elevation taken along line 44 of FIG. 1 in thedirection of the arrows and also showing further details of thestructure of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, there isillustrated therein a compressor 10 which is provided with the dirve ofthe invention. This compressor 10 has a pair of pipes 12 which feedcompressed air to a common pipe 14. From the pipe 14 the compressed airmay be delivered to a suitable tank, for example. The pipes 12 receivethe compressed air from a pair of cylinders 16 which house in theirinteriors a pair of reciprocating pistons 18 one of which is indicatedat the left of FIG. 2 and the other of which is indicated at the rightof FIG. 3. These pistons 18 reciprocate back and forth with suitableclearance in the cylinders 16, air being drawn into the interior of thecylinders in an unillustrated manner through filters 20, one of which isshown in section in FIG. 3. These filters 20 are carried by suitabletapered supports 22. During the pressure strokes of the pistons, air isdelivered therefrom into the interiors of the pipes 12 throughsuitabledischarge valves 24, one of which is shown at the right of FIG. 3.

For compressors of the above type, it is important to reciprocate thepistons 18 at extremely high speeds. For example, each piston should bereciprocated back and forth through approximately 3,000 operating cyclesper minute, or more. The reciprocating drive of the invention is capableof achieving these results in an outstanding manner.

Thus, the pistons 18 are respectively fixed to the opposed ends of apair of coaxial horizontally extending piston rods 26. These piston rodsextend slidably through suitable sealing glands 28 carried by a housingmeans 30 at opposed end wall portions thereof. Suitable compressionsprings 32 surround the piston rods 26 and maintain the sealing glands28 compressed so that a tight sliding fit is assured around the pistonrods 26-so as to maintain the pistons .18 operating at all times in aperfectly dry space.

The piston rods 26 are fixed at their inner ends, which are always inthe interior of the housing means 30, to a crosshead means 34 which ismade of a lightweight material inasmuch as the crosshead means 34 willreciprocate back and forth at high speed, and because of the inertiaassociated therewith will create undesirably large forces unless it ismade of a light-weight material. Preferably the crosshead 34 is made ofa synthetic resin. Many plastics are available for this purpose.

The plastic croshead means 34 is formed with a vertically extending slot36 which receives a slide block 38.

Because. the crosshead means 34 is made of a lightweight material suchas-a suitable synthetic plastic, the opposed .sides of the slot 36fixedly carry guide strips 40 fixed. to thecrosshead means 34 in anysuitable way as by the countersunk screws 42 indicated in FIG. 2. Inorder to assure a proper connection of the screws 42 with the crossheadmeans 34 as well as a proper connection of the piston rods 26 with thecrosshead means .34, the plastic crosshead is molded around internallythreaded sleeves such as the sleeves 44 and 46 (FIG. 2) into which thepiston rods 26 and screws 42 are respectively threaded as illustrated.An effective sliding engagement between the guide strips 40 and theslide block 38 is achieved by a suitable choice of materials for thesecomponents. It is preferred to make the guide strips 40 of steel and theslide block 38 of bronze, preferably phosphor bronze.

A crank pin 48, which is also made of steel, is operatively connectedwith the bronze slide block 38. This crank pin 48 forms part of a rotarycrank means 50 which carries the crank pin 48 at a suitable radialdistance from the axis of rotation of the crank means 50, this axis ofrotation being horizontal and perpendicular to the common axis of thepiston rods 26. As is shown most clearly in FIG. 4, the rotary crankmeans 50 is in the form of a disc, preferably made of steel, and havinga sleeve 52 which surrounds and is fixed with a drive shaft 54 driven bya suitable driving motor 56 which is fixed to the housing 30. The sleeve52 may have a splined or other type of keyed connection with the driveshaft 54 so as to rotate therewith, and a suitable screw 58, forexample, maintains the rotary crank means 50 on the drive shaft 54.

The plastic crosshead means 34 is formed at its upper and lower endswith a pair of bores 60 which extend parallel to the common axis of thepiston rods 26. The crosshead means 34 fixedly carried in the bores 60elongated bearings 62 which form a bearing means surrounding andslidably engaging a pair of stationary guide bars which extend parallelto the common axis of the piston rods 26 and which are fixedly mountedon the housing means 30, extending between the opposed end walls thereofin the manner shown most clearly in FIG. 3. In this case also it ispreferred to make the guide bars 64 of steel and the bearings 62 ofbronze, preferably phosphor bronze.

According to a further feature of the invention a pressurizedlubrication is provided for components such as the crank pin 38 at itsconnection with the slide block 38 and the bearings 62 at their slidableengagement with the guide bars 64. For this purpose the housing 30carries at its front wall an oil pumping unit 66 including a suitabledriving motor 68 and a pump and filter assembly 70 situated in theinterior of the housing 30 in the manner shown in FIG. 4 with theunillustrated inlet of the pump communicating with an unillustrated oilsupply which is maintained in any suitable way in communication with thepump inlet. The oil is pumped under pressure through a suitable pipesystem 74.

One part of the pipe system 74 communicates with a stationaryoil-distributing ring 76 which also is preferably made of a bronze suchas phosphor bronze and which surrounds the rotating steel sleeve 52 atthe exterior thereof. A suitable bracket 78 is fixedly carried by thehousing in the interior thereof (FIG. 4), this bracket 78 being fixed toand supporting the stationary oil ring 76. The oil is delivered from thepipe system 74 in the manner illustrated in FIG. 4 to an internal groove80 which is formed in the interior of the oil ring 76. The sleeve 52 isformed with a bore which communicates with the groove 80 to receive oiltherefrom. Thus the bore in the sleeve 52 includes the axial boreportion 82 closed at its right end by a plug 84 communicating with aradial bore 86 which opens into the groove to receive the pressurizedoil therefrom. The disc 50 is formed with a radial bore 88 closed by aplug 90. This bore 88 extends across an opening 92 in the crank disc 50.The opening 92 is filled by a cylindrical portion 94 of the crank pin48, and the crank pin 48 is held onto the disc 50 by way of a suitablenut and washer assembly 96 carried by a threaded portion of the crankpin 48. The portion 94 which is thus journaled in the disc 50 is formedwith an axial bore 98 which extends through the interior of the crankpin 48 all the way up to the region thereof which is surrounded by theslide block 38. The slide block is held on the crank pin 48 by a secondnut and washer assembly 100. The axial bore 98 is in communication withradial bores 102 formed in the part 94 of the crank pin 48, this part 94having the radial bores 102 in communication with the radial bore 88 ofthe crank disc 50. The axial bore 98 of the crank pin 48 alsocommunicates with radial bores 104 which communicate at their outer endswith external grooves 107 (FIG. 2) and an internal circumferentialgroove 106 formed in the slide block 38. In this way a forcedlubrication is provided at the connection between the crank pin 48 andthe slide block 38.

The pipe system 74 also communicates with a pair of fittings 108 (FIG.3) which deliver the oil under pressure to axial bores 110 which arerespectively formed in the steel guide bars 64. These axial bores 110 inturn communicate with radial bores 112 distributed along the guide bars64 and communicating with the axial bore 110, so that this way the oilunder pressure is delivered to the exterior surfaces of the guide bars64 in order to lubricate the bearings 62 as they slide along the guidebars 64.

Thus, with the above-described pressurized lubricating means it ispossible to maintain the slidable engagement between the bearings 62 andthe guide bars 64 suitably lubricated, and of course with thepressurized lubricating system it is also possible to lubricate thedrive transmission which is deilvered to the slide block 38. Moreover,with the above-described transmission the parts do not develop inertiaforces which are sufficiently great to provide undue stresses.

It has been found from experience that with a system as described aboveit is possible to rotate the shaft 54 at a speed of 3,500 revolutionsper minute, with the bearings 62 travelling along the guide bars 64 andthe slide block 38 sliding along the guide strips 40 at linear speeds onthe order of 62 feet per second. In practice it is possible torecipiocate the pistons at cycles of between 3,000 and 6,000 cycles perminute. The hydraulic pressurized lubricating means of the invention isself-contained and is capable of operating at pressures of 2,000 psi.The bronze used for the slide block 38, the oil ring 76, and thebearings 62 is a special high quality phosphor bronze with an extremelyhigh strength achieved by cold-working. In practice it has been foundthat the thermal stability of this bearing material is constant up to572F (300C) with the stability then decreasing only slowly beyond thistemperature.

In practice an unlimited working life for the entire drive mechanism canbe assured because of the negligible wear achieved with the invention.

It will be noted from FIG. 2 that the exterior surface of the crank pin,where it is surrounded by the slide block 38, is formed with a spiralgroove 107 communicatingwith bore 104 to improve the distribution of thelubricant.

What is claimed is: v

1. For use with horizontally arranged opposed compressor pistons, a pairof coaxial horizontal piston rods,

. crosshead means situated between and fixed to said piston rods, saidcrosshead means being formed with a vertically extending slot and havingopposed upper and lower ends respectively formed with bores extendingtherethrough parallel to said piston rods, a pair of bearing meansrespectively situated in said bores and fixed to said crosshead means, apair of guide bars extending parallel to said piston rods through saidbearing means, said bearing means having sliding engagement with respectto said guide bars, housing means carrying said guide bars and housingsaid guide bars and crosshead means in the interior of said housingmeans, a slide block situated in said slot of said crosshead means forslidable movement vertically along said slot, rotary crank means carriedby said housing means and having a horizontal axis of rotation which isperpendicular to the common axis of said piston rods, said rotary crankmeans including a crank pin displaced by a predetermined radial distancefrom said axis of rotation of said rotary crank means and operativelyconnected with said slide block for reciprocating the latter verticallyin said slot of said crosshead means while displacing said crossheadmean back and forth along said guide bars, and pressurized lubricatingmeans operatively connected with said crank pin and said pair of bearingmeans for lubricating said crank pin and said pair of bearing means,said pressurized lubricating means including a pump means carried bysaid housing means and communicating with a lower interior portionthereof where an oil bath is located, an oil ring carried by saidhousing means in the interior thereof and surrounding said rotary crankmeans, said oil ring communicating with said pump means to be fed withpressurized oil thereby and said oil ring having an interior grooveprovided by said pump means with a supply of oil, said rotary crankmeans being formed with an inter- 6 nal bore communicating with saidgroove "of said oil ring and receiving pressurized oil therefrom, andsaid crank pin being formed with internal bores communicating with saidbore of said rotary crank means and with an inner surfacae of said slideblock which surrounds said crank pin so that the presssurized oil isdelivered from said rotary crank means along the interior of said crankpin to the inner surface of said slide block which surrounds said crankpin.

.2. The combination of claim 1 and wherein said crosshead means is madeof a light-weight material and carries a pair of guide strips extendingalong opposed parallel vertical sides of said slot, said guide stripsslidably engaging said guide block.

3. The combination of claim 2 and wherein said guide strips are made ofsteel while said slide block is made of bronze.

4. The combination of claim 1 and wherein said guide bars are made ofsteel and saidpair of bearing means are made of bronze.

5. The combination of claim 1 and wherein said rotary crank means andcrank pin are made of steel while said slide block is made of bronze.

6. The combination of claim 5 and wherein a pair of steel guide stripsare carried by said crosshead means along opposed vertical sides of saidslot and slidably engage said bronze slide block.

7. The combination of claim 1 and wherein said guide bars arerespectively formed with bores communicating with the outer surface ofsaid guide bars and also communicating with said pump means to receivepressurized oil therefrom to be delivered to the outer surface of saidguide bars for lubricating said bearing means.

8. The combination of claim 1 and wherein said crosshead means is madeof a plastic material.

9. The combination of claim 1 and wherein a pair of sealing gland meansrespectively slidably engage and surround said piston rods formaintaining pistons connected to said piston rods in a dry condition.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3-920'098 DATED November 18, 1975 |N\/ ENTOR(S) WalterSchroeder It is certi fied that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the heading, after the inventor's name, the address should read: --6s. Coria St., Brownsville, Texas 78520--.

Signed and Scaled this Twenty-sixth Day of April 1977 [SEAL] Arrest:

RU'IH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofParents and Trademarks

1. For use with horizontally arranged opposed compressor pistons, a pairof coaxial horizontal piston rods, crosshead means situated between andfixed to said piston rods, said crosshead means being formed with avertically extending slot and having opposed upper and lower endsrespectively formed with bores extending therethrough parallel to saidpiston rods, a Pair of bearing means respectively situated in said boresand fixed to said crosshead means, a pair of guide bars extendingparallel to said piston rods through said bearing means, said bearingmeans having sliding engagement with respect to said guide bars, housingmeans carrying said guide bars and housing said guide bars and crossheadmeans in the interior of said housing means, a slide block situated insaid slot of said crosshead means for slidable movement vertically alongsaid slot, rotary crank means carried by said housing means and having ahorizontal axis of rotation which is perpendicular to the common axis ofsaid piston rods, said rotary crank means including a crank pindisplaced by a predetermined radial distance from said axis of rotationof said rotary crank means and operatively connected with said slideblock for reciprocating the latter vertically in said slot of saidcrosshead means while displacing said crosshead mean back and forthalong said guide bars, and pressurized lubricating means operativelyconnected with said crank pin and said pair of bearing means forlubricating said crank pin and said pair of bearing means, saidpressurized lubricating means including a pump means carried by saidhousing means and communicating with a lower interior portion thereofwhere an oil bath is located, an oil ring carried by said housing meansin the interior thereof and surrounding said rotary crank means, saidoil ring communicating with said pump means to be fed with pressurizedoil thereby and said oil ring having an interior groove provided by saidpump means with a supply of oil, said rotary crank means being formedwith an internal bore communicating with said groove of said oil ringand receiving pressurized oil therefrom, and said crank pin being formedwith internal bores communicating with said bore of said rotary crankmeans and with an inner surfacae of said slide block which surroundssaid crank pin so that the presssurized oil is delivered from saidrotary crank means along the interior of said crank pin to the innersurface of said slide block which surrounds said crank pin.
 2. Thecombination of claim 1 and wherein said crosshead means is made of alight-weight material and carries a pair of guide strips extending alongopposed parallel vertical sides of said slot, said guide strips slidablyengaging said guide block.
 3. The combination of claim 2 and whereinsaid guide strips are made of steel while said slide block is made ofbronze.
 4. The combination of claim 1 and wherein said guide bars aremade of steel and said pair of bearing means are made of bronze.
 5. Thecombination of claim 1 and wherein said rotary crank means and crank pinare made of steel while said slide block is made of bronze.
 6. Thecombination of claim 5 and wherein a pair of steel guide strips arecarried by said crosshead means along opposed vertical sides of saidslot and slidably engage said bronze slide block.
 7. The combination ofclaim 1 and wherein said guide bars are respectively formed with borescommunicating with the outer surface of said guide bars and alsocommunicating with said pump means to receive pressurized oil therefromto be delivered to the outer surface of said guide bars for lubricatingsaid bearing means.
 8. The combination of claim 1 and wherein saidcrosshead means is made of a plastic material.
 9. The combination ofclaim 1 and wherein a pair of sealing gland means respectively slidablyengage and surround said piston rods for maintaining pistons connectedto said piston rods in a dry condition.